I describe a new parallel-processing stellar photometry code
called QLWFPC2 which is designed to do quick-look analysis
of two entire WFPC2 observations from the Hubble Space
Telescope in under 5 seconds using a fast Beowulf cluster
with a Gigabit Ethernet local network. This program is
written in ANSI/ISO C and uses the MPICH implementation of
the Message Passing Interface from the Argonne National
Laboratory for the parallel-processing communications, the
CFITSIO library (from HEASARC at NASA's GSFC) for reading
the standard FITS files from the HST Data Archive and the
Parameter Interface Library (from the INTEGRAL Science Data
Center) for the IRAF parameter-file user interface. QLWFPC2
running on 4 processors takes about 2.4 seconds to analyze
WFPC2 archive datasets u37ga407r.c0.fits (F555W; 300 s) and
u37ga401r.c0.fits (F814W; 300 s) of M54 (NGC 6715) which is
the bright massive globular cluster near the center of the
nearby Sagittarius dwarf spheroidal galaxy. The analysis of
these HST observations of M54 lead to the serendipitous
discovery of more than 50 new bright variable stars in the
central region of M54. Most of the candidate variables stars
are found on the PC1 images of the cluster center --- a
region where no variables have been reported by previous
ground-based studies of variables in M54. This discovery is
an example of how QLWFPC2 can be used to quickly explore the
time domain of observations in the HST Data Archive. This
work is supported by a grant from the National Aeronautics
and Space Administration (NASA), Order No. S-13811-G, which
was awarded by the Applied Information Systems Research
Program (AISRP) of NASA's Office of Space Science (NRA
01-OSS-01).

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